2015—2020年昆山市农田土壤5种重金属监测结果分析

Analysis on monitoring results of five heavy metals in agricultural soil of Kunshan City from 2015-2020

目的分析昆山市农田土壤铅、镉、铬、汞和砷5种重金属元素含量现状,为农田重金属污染防治提供基础资料。方法 2015—2020年,采集昆山市农田土壤120份并监测铅、镉、铬、汞和砷含量,采用单项污染指数法和综合污染指数法对土壤污染状况进行评价。结果 120份农田土壤中,铅、镉、铬、汞和砷的含量分别为32.150、0.149、64.677、0.187和8.890 mg/kg,镉元素超标率为3.33%(4/120),汞元素超标率为1.7%(2/120),其他元素合格率均为100.0%。5种元素的污染范围铅>镉>汞,单项污染指数结果为镉(0.437)>汞(0.409)>砷(0.360)>铬(0.222)>铅(0.111),综合污染指数显示昆山市总体为0.454,各区镇综合污染指数范围为0.362~0.565,处于清洁水平。结论 2015—2020年昆山市农田土壤重金属总体处于清洁水平,以镉、汞和砷的污染为主,镉和汞有超标风险,铅元素污染较轻但分布广泛,铬污染较轻。

Objective To analyze the content status of five heavy metals,including lead,cadmium,chromium,mercury and arsenic,in agricultural soil of Kunshan City,provide basic data for the prevention and control of heavy metal pollution in farmland.Methods Totally 120 samples of agricultural soil in Kunshan City were collected,and the contents of lead, cadmium,chromium,mercury and arsenic were monitored from 2015-2020. The situation of soil pollution was evaluated through single pollution index and the integrated pollution index. Results The average content of lead,cadmium,chromium,mercury and arsenic in 120 samples of soil was 32.150,0.149,64.677,0.187 and 8.890 mg/kg,respectively. The over-standard rate of cadmium was 3.33%(4/120),and the over-standard rate of mercury was 1.7%(2/120),while the qualified rates of other elements were 100.0%. The sequence of contamination range was lead>cadmium>mercury. The results of single pollution index were as follows :cadmium(0.437)>mercury(0.409) >arsenic(0.360) >chromium(0.222) >lead(0.111). The results of integrated pollution index showed that it was0.454 in Kunshan City and 0.362-0.565 in districts and towns,which was at a clean level. Conclusion The heavy metals in agricultural soil of Kunshan City from 2015-2020 is in clean level generally. The mainly pollution elements are cadmium,mercury and arsenic,cadmium and mercury have the risk of exceeding the standard,lead element pollution is lighter but widely distributed,and chromium pollution is lighter.